This invention relates to the field of organic chemistry, and more particularly to novel 3,5-disubstituted-2,4,6-triiodoanilides of polyhydroxy-monobasic acids useful as non-ionic x-ray contrast media.
As is known, many 2,4,6-triiodobenzoic acid derivatives have been proposed and used as x-ray contrast agents. In general, it has been the practice to convert these compounds to salts, such as for example, the sodium and N-methylglucamine salts in order to render the compounds water-soluble and suitable for intravenous administration.
More recently, Almen et al. (U.S. Pat. No. 3,701,771, dated Oct. 31, 1972) have disclosed certain non-ionic N-(2,4,6-triiodobenzoyl)-sugar amines which are stated to be useful as x-ray contrast agents in the cerebrospinal cavities. In these compounds, a polyhydroxyalkyl chain is coupled to an iodoaromatic moiety in order to impart water solubility without resorting to ionic species. Certain of the non-ionic compounds disclosed in this patent were reported to be highly soluble in water while others were reported to have a medium or low water solubility.
In certain instances, non-ionic x-ray contrast media have been found to be less toxic than their ionic counterparts. This is believed to be due at least in part to the fact that the non-ionic compounds, being substantially non-ionized in aqueous solution, create less of an osmotic imbalance than do ionic compounds, i.e., non-ionic x-ray contrast media contribute only one molecular species per iodinated moiety as compared to ionic x-ray contrast media which contribute two or more species per iodinated moiety.
An interest has developed, therefore, in the synthesis of water-soluble, non-ionic x-ray contrast media possessing low toxicity and high iodine content for use in the x-ray visualization of areas of the body such as, for example, the cardiovascular system where high concentrations of contrast media are required in order to provide sufficient opacity.